A Study on the Statistical Characterisics of Fatigue Crack Propagation Rate in Turbine Rotor Steel(I)

J. Ocean Eng. Technol. 1987;1(2):83-92.

터빈 로터강의 피로크랙전파속도의 확률특성 연구( I )

오세욱,이치우,정순호

동아대학교 기계공학과,경남대학교 기계설계학과,한국중공 기술연구소

Keywords: turbine rotor steel, fatigue crack growth rate

핵심용어: 터빈 로터용 강, 피로크랙전파속도, 확률특성

Abstract

Inorder ot estimate the running life of turbine rotors, fatigue crack propagation low, da/dN = C(${DELTA}K)^m$, proposed by paris et al. has been widely applied. In this study, fatigue crack propagation rates for 16 samples of 1% Cr-Mo-V rotor steel were measured and statistical characteristics of m and C values in above equation were reviewed. The results are summarized as follows. 1. C and m follow a log-normal distribution and normal distribution, respectively. And the relation of C and shows a strong negative correlation. 2. Fatigue crack propagation equation can be expressed as da/dN=$4.11{ imes}10^{-4}({Delta}K/153.8)^m$, introducing the ralationship C=$C_oK_o^{-m}$. In this case, contribution of $C_o$ distribution to the distribution of log C shows very small compared to degrees of contribution by m.